1. Field of the Invention
The subject invention pertains to expansible chamber devices. More particularly, this invention pertains to such devices having plural, unitarily mounted cylinders having a liner retained by closure associated means. The subject invention also pertains to ordnance; more particularly, it pertains to the shape and composition of a projectile defeating element.
2. Description of the Prior Art
It is known to provide resistance to damage, such as ballistically caused damage by projectile penetration in combat aircraft, in a hydraulic actuator, by the use of redundant cylinder assemblies, so that in the event of damage to one assembly the other assembly can continue to actuate the element. Such an actuator is particularly advantageous in a combat aircraft in which penetration of an actuator by a projectile must be anticipated and in which failure may result in loss of the aircraft.
However, the mere provision of a plurality of cylinder, assemblies is not always effective in providing continued actuation because, in the event of damage to one assembly, the damage may deform a cylinder wall, jamming the actuator even though another assembly is undamaged. A particularly serious form of such damage in combat aircraft is due to penetration of a hydraulic cylinder wall by a projectile, resulting in "petals," which are leaf-like portions of the wall surrounding the opening formed by the projectile as it pierces the wall and which extend into the path of a piston therein.
It is known to alleviate this problem by an actuator in which each cylinder assembly has a tubular inner liner in which the corresponding piston moves this liner being relatively thin and/or of relatively weak material so that petals are sheared off by piston movement. Since such a liner is necessarily weak, it cannot resist the forces generated by hydraulic pressure in normal operation of the actuator. It is therefore necessary to surround the liner by a suitable pressure resisting structure, typically steel.
It is also known to alleviate the problem of such jamming by penetration caused petals in redundant cylinder hydraulic actuators by use of frangible pistons and other elements slotted and scored so as to break when urged into engagement with such a petal from a conventional heavy metal cylinder wall.
In addition, it is known to provide pressure vessels of lightweight construction and resistant to shattering when punctured by utilizing a metal liner, which prevents leakage of the vessel contents and is wrapped with resin impregnated filament to withstand the forces generated by pressure within the vessel, these forces varying so that the elastic limit of the metal liner is continually exceeded. Such vessels, insofar as known to the applicant, are static devices.